Traffic light controller



Dec. 10, 1963 J. E. RAMSEY 3,

TRAFFIC LIGHT CONTROLLER Filed March 5, 1962 3 Sheets-Sheet l OSCILLATOROSCILLATOR OSCILLATOR L 300cy 400cy 500cy M8 T9 Antx i TRANSMITTER Fig.l

I INVEN TOR. JAMES E. RAMSEY WWW Dec. 10, 1963 J. E. RAMSEY 3,114,127

TRAFFIC LIGHT CONTROLLER Filed March 5, 1962 3 Sheets-Sheet 2 RADIORECEIVER ACTUATOR MODULATION SENSITIVE MANUAL FLASH MAGN'ET INVENTOR.Fig. 2 JAMES E. RAMSEY Dec. 10, 1963 J. E. RAMSEY TRAFFIC LIGHTCONTROLLER Filed March 5, 1962 3 Sheets-Sheet 3 2o RADIO RECEIVER 7 ZOL/ 2| MODULATION-SENSITIVE [1 ACTUATOR Hi -E U J7 48 INVENTOR. Fig 3JAMES E. RAMSEY BYWW AWORNEYS United States Patent 3,114,127 TRAFFICLIGHT CONTROLLER James E. Ramsey, New Castle, Pa., assignor, by mesneassignments, to Electronic Traiiie Control Inc., New Castle, Pa., acorporation of Pennsylvania Filed Mar. 5, 1962, Ser. No. 177,413 14Claims. (Cl. 340-32) This invention relates to emergency traflic-lightcontroller systems, and more particularly relates to novel improvementsin remotely-controlled traflic-light systems whereby an emergencyvehicle such as an ambulance or a police car can by remote means locatedwithin the vehicle control traffic lights which it is approaching so asto present a go signal along the path of the vehicle and red lights tovehicles approaching on crossing streets.

It is a principal object of this invention to provide radio controlmeans for controlling traflic lights in which a transmitter of limitedrange is located within the emergency vehicle, or alternatively in atratfic-control helicopter, and in which receivers are located at eachtrafiiclight-controlled intersection, the receivers being tuned to thetransmitter carrier frequency.

It is another very important object of the present invention to providea radio frequency control system em ploying control signals which arecoded with at least two different modulating frequencies which must bothbe present at the receiver in order to switch over the traffic lightcontroller from local to remote, whereby accidental interference withthe normal function of the traflic-controller which might be caused byspurious signals is vir tually precluded.

The present system includes the remotely-located transmitter in thevehicle and equipped with two or more push buttons having identifyingmarkers thereon. In order to assist the driver of the vehicle todetermine which button should be pushed as a light-controlledintersection is approached, the identifying markers on the buttons arealso posted on placards or discs attached to the utility polesapproaching the intersection, each of these placards displaying theidentifying marker corre sponding with the marker on the push buttonthat should be pressed by the operator in order to have the right-ofwaywhen the vehicle enters the intersection. More than two push buttons mayadvantageously be provided in the vehicle for the purpose of controllingthe lights at a more complicated intersection having, for example, aleft-turn light or having perhaps a non-rectangular intersectionrequiring a selection as between two possible exit direc* tions. Thesespecial situations could generally be covered by a third button, orperhaps several additional-buttons in the vehicle having markerscorresponding with the more specialized alternative-light patterns. Atany rate, each of the push buttons is coupled with a modulation signalgenerator having a unique frequency or other characteristic, the presentinvention being illustrated in connection with audio frequencymodulation oscillators which are tuning-fork stabilized.

As stated above, in order to avoid unwanted actuation of thetraffic-light controller by spurious signals two different modulationsare used in the transmission of each complete control signal, one ofwhich modulations is a coding signal which is common to all of thebuttons which can be pressed in the vehicle and serves to enable thecontroller for remote control, and the other of which signals is uniqueto the particular button depressed in the vehicle and identifies apreferred direction of travel of the vehicle. In addition, the pushbuttons are provided with slow return means, such as dashpot means, sothat once the button is depressed, it returns from the down positionover an interval comprising a certain number of seconds designed toassure that the message from the vehicle will be of sufficient durationto actuate the trafficlight controller. The push buttons, theirmodulating os cillators, and the additional modulation oscillator whichis common to all of the push buttons are all connected to modulate theoutput of a low-powered transmitter.

This low-powered transmitter is picked up at each controlledintersection by a small radio receiver having an omnidirectional antennaand connected to the trafiic-light controller. The radio receiver isconnected with a tuned modulation-sensitive relay means which, whensupplied with the modulation frequency which is common to all of thepush buttons plus one of the other modulation frequencies unique to oneof the push buttons, actuate sets of switching contacts which cause thestandard trafliclight controller itself to interrupt its normalautomatic function to provide the type of light-control selected by theapproaching vehicle, as evidenced by the particular unique modulationpresent in the received control signal. This signal continues to affectthe traflic-light controller for a predetermined interval as determinedby a timer in the tuned relay system, and at the end of this intervalthe relays are released and the automatic function of the controllerresumes.

Another object of the invention is to provide a remotecontrol systemwhich can be connected to a standard trafiic-light controller, such asthe EA70 Series Controller manufactured by the Eagle Signal Corporation,and which system when so connected can take over control therefrom foremergency purposes, and subsequently return control to the controllerunit in such a way that the latter can then synchronize itself withother traflic lights at other intersections so that the temporarydisruption does not throw the controller out of synchronism with theother controlled intersections once the emergency has passed.

Other objects and advantages of the invention, and a working embodimentthereof, will become apparent dur-' ing the following discussion of thedrawings, wherein:

FIG. 1 is a schematic diagram illustrating a transmitter according tothe present invention to be located in an emergency vehicle;

FIG. 2 is a schematic diagram illustrating the stationary equipment tobe located at the trafiic-light controller, and showing one suchcontroller, the diagram of which has been somewhat simplified to omitdetails which are unimportant to the present disclosure; and

FIG. 3 is a schematic diagram illustrating in greater detail themodulation-sensitive actuator relay means shown in block diagram form inFIG. 2.

Referring now to the drawings, and in particular to FIG. 1, whichillustrates the special transmitting equipment to be located in theemergency vehicle, this equipment includes an antenna Ant locatedconveniently on the vehicle (not shown) and connected with a transmitter1 which in turn is provided with coded modulation frequencies ashereinafter discussed. The equipment also includes, in the presentillustrative example, three push buttons 2, 3 and 4 which arerespectively supported by and controlled by three dash-pot means 2a, 3aand 4a, these dash-pot means being of any conventional design and slowlyreleasing the push buttons upwardly once they have been depressed by thedriver of the vehicle. Each of the push buttons includes a shaft,respectively labeled 2b, 3b and 4b, and each shaft having a projectionrespectively labeled 2c, 30 and 40 to actuate the spaced arms on anadjacent two-circuit switch. For instance, the projection 2c actuatesthe arms on a switch 6, but only during rising of the shaft 2b in thedirection of the arrow located thereon. In other words, when the pushbutton 2 is depressed the projection 2c moves downwardly toward thedash-pot 2a and then as the button is released, the projection 2c risesupwardly first raising the arm 6a so as to close the lower circuit ofthe switch 6 and then at a somewhat later instant raising the arm 61) soas to close the upper circuit of the switch. The switches 7 and 8 areoperated in an identical manner respectively by the projections 3c and4c. All three of the lower circuits of the switches 6, 7 and 8 areconnected to a wire 9 which wire serves to energize the ZOO-cycle tuningfork oscillator it) when the wire 9 is grounded.

The schematic diagram of the oscillator 19 is illustrated in FIG. 1 andincludes a tuning fork Fa connected between two windings 10b and 190which are provided with bias by a resistive voltage divider and whichwindings control a transistor lttd which furnishes the gain necessary tosustain oscillations. This type of oscillator is well known and will notbe discussed in any greater detail because of the fact that theoscillator is available as a commercial component from Stephens-Arnold,Inc, South Boston, Mass. Incidentally, the potentiometer adjustment 10aserves to adjust the oscillation for maximum amplitude. Three othersimilar oscillators 11, 12 and 13 are illustrated.

The oscillator 11 is tuned to a different selected frequency, forinstance 300 cycles in the present illustration, and this oscillator isconnected by a wire 15 to the upper switch contacts 612 for control bythe switch 6. Thus, as the shaft 2b returns upwardly at the push button2, the oscillator 10 is first energized and the oscillator 11 isenergized thereafter, and these two modulations are sequentiallytransmitted by the transmitter 1 to the receiving equipment at thecontroller, to be described hereinafter. In a similar manner, theoscillator 12, for example 400 cycles, is connected by a Wire 16 to theupper circuit of the push button 3, and the oscillator 13 is connectedby a wire 17 to the upper circuit of the switch 8. If the push button 3is actuated, the ZOO-cycle oscillator is first energized, andsubsequently the 400-cycle oscillator 12 is energized; but on the otherhand if the push button 4 is depressed, the 2G0-cycle oscillator It isfirst energized, followed by energization of the SOD-cycle oscillator 13as the projection 4c on the push button 4 travels upwardly past theswitch 8. The outputs of oscillators 1t), 11, 12 and 13 are allconnected to the wires 18 and 18 which lead into the transmitter 1 so asto modulate the transmitter in accordance with whichever of the pushbuttons is depressed.

The oscillators 1t), 11, 12 and 13 are connected with a source of supplyvoltage represented by the plus sign at the wire leading from eachoscillator, this wire being suitably connected to a battery, such as thebattery of the emergency vehicle.

Turning now to the description of the contents of FIGS. 2 and 3, whichare best described simultaneously, these figures illustrate thestationary units located at the tratficlight controller in eachintersection. These units comprise a conventional radio frequencyreceiver 26 coupled with a small receiving antenna Ant located near theinplaying three different colors in each direction. On the main highway,there are three lights: green, amber and red, and labeled 1G, 1A and IRin FIG. 2. On the secondary highway crossing the main highway there arealso three lights: green, amber and red, which lights are labeled 26, 2Aand 2R, and all of these lights are connected with one side of a sourceof power schematically represented by the plug P at the bottom of FIG.2.

The other ends of each of these lights is connected with an arm of adifferent cam-operated switch each including a cam carried on a commoncam shaft S intermittently rotated by a ratchet stepping motor Moperating, through suitable mechanical linkage, a ratchet wheel Wadvanced tersection, the receiver 20 being connected withmodulation-sensitive actuators 21 which receive the radio-frequencysignals picked up by the receiver, and which contain tunedfrequency-sensitive relays which convert the coded modulation from thetransmitted signal of the vehicle into positions of switch contactswhich are connected into the conventional traffic-signal controller K inorder to take over control thereof upon receipt of a remote-controlsignal.

by a pawl shown adjacent to the wheel. The ratchet motor is of aweight-operated type such that when the winding of the motor isenergized, a weight (not shown) attached to the pawl is raised, and whenthe circuit is roken to the ratchet motor winding, the weight falls andadvances the shaft one ratchet position, which amounts to apredetermined number of degrees on the standard controller. In addition,a synchronous timing motor N having a conventional switching dial runsall of the time and is controlled by a switch N by which the motor canbe shut off during servicing of the equipment. Otherwise, the switch N'is normally closed so that the synchronous motor runs all of the time.This motor has a plurality of contacts on its switching dial which areclosed and opened in sequence by the motor N. There is an impulsecontact I controlled by the synchronous motor, and there is a releasecontact R which is also sequentially controlled by the synchronoustiming motor N. Finally, there is a set of flasher contacts P which arecontinuously closed and opened at a relatively higher rate of speed sothat when these contacts are placed in circuit by other switching meansas subsequently described, the lights can be made to perform a flashingfunction, as is familiar to experienced motorists.

There is also an automatic-manual switch C located in the traffiolightcontroller K and arranged in such a manner that when connected toautomatic, the syn-.

chronous motor N timing system automatically advances the stepping motorM to rotate the shaft S and operate the lights in a predeterminedsequence, and when the switch C is connected to the manual position, theautomatic feature is disconnected and the stepping ratchet is advancedonly by the manual control switch X, this switch energizing the ratchetmotor winding M each time the switch is depressed and thereby raisingthe weight on the pawl as mentioned previously, but releasing the weightto fall and advance the shaft S one position whenever the manual pushbutton X is released. An insulating strip B shown just above the camshaft S supports a plurality of contacts all connected in parallel andconnected to the power line P through the signal shutdown switch Y whichis normally closed. This plurality of contacts supported on theinsulator strip B corresponds in each case with a contact arm such asthe arm A, which arm is actuated by a lobe L on the associated cam asthe shaft S rotates. This structure is conventional and very well knownin connection with signal controllers and needs no further explanation.At the right end of the insulating strip B and the cam shaft S areillustrated several other cams and switch arms shown in dotted lines toillustrate the manner in which further circuits are added to the camshaft in order to control more complicated intersections havingleft-turn lights and other similar additional functions.

As the cam shaft rotates the circuits are sequentially completed throughthe arms A and through the appropriate lights, such as the light 1R, andthen to the other side of the power line P". One additional cam is shownon the shaft S as associated with a contact arm A connected in serieswith the impulse contact switch I which is continuously rotated by thesynchronous timing motor N. This contact serves to re-synchronize thecam shaft S with the synchronous motor N position. This is anotherwell-known feature of traflic controllers by which, once for eachrevolution of the cam shaft S, the arm A opens and remains open untilthe synchronous timing motor catches up with the position of the shaftS. In this way, the shaft, if out of step with the motor N, is caused topause until the synchronous motor N reaches a certain position, and thenthe shaft proceeds again in step with the synchronous timing motor. Thisconventional feature is of importance because of the fact that thetraflic-light controller synchronous motor N is synchronized with themotors of the other controllers for diiferent intersections and thismotor is never interrupted or stopped. On the other hand, the positionof shaft S is sometimes separated from control by the synchronous timingmotor N as when being controlled by the modulation-sensitive actuator21. When the control by this actuator has ceased, however, it is thennecessary for the ratchet motor M to be controlled once again by thesynchronous timing motor N, and it is the delay caused by the cam andthe wiper arm at A which permits the ratchet motor to wait until thesynchronous motor reaches a certain position before falling into steptherewith. At the left end of the shaft S there are three additionalauxiliary cams serving the purpose to be hereinafter described inconnection with the description of the modulation-sensitive actuator 21shown in detail in FIG. 3. In further describing the portion of thetraflic signal controller K illustrated in FIG. 2, this system alsoincludes flasher means controlled by the switch Z such that when thisswitch is closed current is passed through the flash magnet Q havingcontacts Q1, Q2 and Q3, all of which are normally open. This magnet issupplied with current from the line P" on one side and from the line Pthrough the switch Z on the other side, and the energizing of the flashmagnet Q also causes opening of the contacts Q4 which are normallyclosed. This breaks the circuit of the automatic control through theswitch C so that the ratchet motor is no longer caused to rotate in stepwith the synchronous timing motor. However, as stated above, thissynchronous motor continuously makes and breaks the set of contactsmarked F and thereby connects current from the power line P through theswitch Y and the flasher F and through the contacts Q3 and Q2 intowhichever of the electric-light bulbs is connected with the contacts Q2.For instance, the red light of the secondary highway labeled 2R is shownconnected with the contacts Q2 so that this light will flash redcontinuously as the intermittent flasher circuit through the contacts Fis made and broken by rotation of the synchronous motor N.

Turning now to a description of the structure and manner of operation ofthe modulation-sensitive actuator, it will be seen that in both FIGS. 2and 3 a bank of coupling jacks is provided between the actuator 21 andthe controller K, these jacks comprising connections marked J1, J2, J3,J4, J5, J6, J7 and IS, the same contacts being duplicated in both FIGS.2 and 3. The jacks J4 and J8 carry power respectively from the signalcontroller K to the modulation-sensitive actuator 21, respectively fromthe two sides of the power line P" and P. These power lines connect withan ordinary bridge rectifier 22 which delivers to the lines 23 and 24positive and negative DC. voltage filtered by a capacitor 25 in a mannerknown per se. This DC. voltage is used to energize the relays which arepresent in the modulationsentitive actuator 21 and which will behereinafter described. There are four of these relays each having a DC.winding, these windings being labeled 30, 31, 32 and 33. All of thesewindings have their left ends connected with the D.C. power line 24.Across each of these windings is an RC delay circuit comprising a seriescapacitor and resistor, these circuits being labeled 30d, 31d, 32d and33d, and these RC circuits serving in a manner well known per se todelay opening of the relay for a short interval of time after thecircuit thereto is broken.

The right sides of each of the windings 31, 32 and 33 are respectivelyconnected through switch contacts which control whether or not currentis passed from the other side of the power line 23 to these fourwindings, which incidentally can not all be energized at once as willpresently appear.

Among the contacts which are connected in series with the windings ofthe relays 31, 32 and 33 are the contacts of four tunedfrequency-sensitive relays, including the relay 40 tuned to 200 cycles,the relay 41 tuned to 300 cycles, the relay 42 tuned to 400 cycles, andthe relay 43 tuned to 500 cycles, these relays each having an energizingwinding which is coupled to the modulation output signal of the radioreceiver 20 by the wires 20a and 2012. Thus, whatever modulation tonesmay be present on the wires 20a and 20b from the receiver 20 willenergize the resonant windings associated with the relays 40, 41, 42 and43, and where the modulation tone on the wires 2tta-20b corresponds withthe tuning of the winding of the resonant relay, that relay switch 46,41, 42 or 43 will be closed.

For example, suppose that the first push buutton 2 shown in FIG. 1 isdepressed, meaning that the transmitter first transmits a ZOO-cycle toneand then subsequently transmits a 300-cycle tone. When the ZOO-cycletone is received by the receiver 20, it appears on the wires 20a and 20bbut it can actuate only the relay 40 which is resonant at thatfrequency. The relay contacts 40 therefore close and deliver power fromthe power line 23 through the contacts 40, into the coil 30 which causesthis relay to close thereby closing the contacts 30a, 30b and 300. Therelay 30 remains energized, and this energization closes all of thecontacts 30a, 30b, 30c and 30h, the latter contacts comprising a holdcircuit continuously maintaining power through the relay winding 30 tohold it closed. Also, a timer 35 is included in series with the contacts30h and is turned on thereby, and this timer runs for a predeterminedinterval, for instance 15 seconds, and then opens its normally-closedcontact 35a. When these contacts open, the hold circuit through thecontacts 30h is broken and the relay coil 30a is then permitted to openfor the purpose to be hereinafter described. The time of operation ofthe timer 35, before it releases the winding 30 by opening itsnormally-closed contact 35a, is adjusted to permit the emergency vehicletime to pass through the intersection and be gone.

As a result of the closing of the switch 30, the controller K is placedin an enabled condition so that if the vehicle transmitter 1 transmits a300, a 400, or a 500 cycle signal, the controller will react thereto,but in every case actuation occurs only if the receiver has received theZOO-cycle coding or enabling signal plus one of the other signals at300, 400 or 500 cycles per second. This enabling condition isestablished when the relay 30 has been actuated to close the contacts30a, 30b, and 30c and its own holding contacts 30h. The closing of thecontacts 30a energizes the DC. power line 23a by connecting it to theoutput of the rectifier 22 on the positive side thereof, and when thisline is energized, current can be passed from they rectifier through oneof the other windings 31,32 or 33 if a tone appears on the output lines20a and 20b from the receiver which tone corresponds with the resonantfrequency of one of the relays 41, 42 or 43. Assume, for example, thatthe transmitter 1n the vehicle has just put out a SOD-cycle modulation,which modulation closes the switch 41 and energizes the winding 31. Whenthis occurs, the normally-open hold contacts 31h are energized, whichcontactsv maintain the line 31 energized through normally-closedcontacts 32a and 33a of the other relays shown in series with the line,which contacts will be presently described.

On the other hand, if a 400-cycle tone should appear at the output ofthe receiver, the resonant relay 42 would then close and would therebyhave energized the winding 32 to close the hold contact 32h. Likewise, a500- cycle tone would have energized the resonant relay 43 to energizethe winding of the relay 33 and close the hold contacts 33h in order toretain this energization. The resonant relays 40, 41, 42 and 43 have notbeen described in greater detail in this specification because of thefact that they are also manufactured items commercially available fromStephens-Arnold, Inc.

The relays 3t), 31, 32 and 33 have other contacts besides their holdcontacts. For example, the relay 31 has contacts 31a, 31b and 310 all ofwhich are normally closed, and also includes a normally-open contact311:. Similarly, the relay 32 has normally-closed contacts 32a, 32b and320, and normally-open contact 32c. The relay 33 has normally-closedcontacts 33a, 33b and 330, and normally-open contacts 33e. By inspectionit will be seen that when the relay 31 is actuated it can close only ifnormally-closed contacts 32a and 33a in series with its winding areclosed. Thus if the relay 32 is actuated, it becomes impossible toactuate relays 31 or 33 because the normally-closed contacts 32:: and32b are open. Similarly, when the relay 33 is actuated, relays 31 and 32can not be energized because the normally-closed contacts 33a and 33bare opened and in series with the respective other relay windings. Thus,these normally-closed contacts prevent actuation of more than one of therelays 31, 32 or 33 at a time. Moreover, when one of the relays, such asthe relay 31, is actuated, the normally-open contact 31e becomes closedand connects power from the power line P to the leftmost auxiliary cam45, and the connector J1 and this cam switch depending on the positionof the shaft S will actuate the flash magnet Q and cause flashing ofwhatever lights are connected to the flasher F via contacts such ascontacts Q2 and Q3. On the other hand, if the relay 32, FIG. 3, isenergized, the normally-open contact 32c will be closed, and willenergize a circuit past the cam switch 46, assuming that the cam is in aposition to close the contact associated therewith. If it is in suchposition, again the flash magnet Q will be energized and will flashwhatever light happens to be connected by the light-controlling cams onthe cam shaft at the time. A similar circuit also works in connectionwith the relay 33, whereby if this relay is energized, the contacts 33care closed to energize a circuit by way of the cam 47 and the contactsassociated therewith, and again energize the flash magnet Q. However,note that none of the switch contacts Sle, 322 or 33c can affect thetrafiic controller cam system unless the relay 30 is closed so as toclose the normally-open contacts 30b, here again requiring that thecoding relay 30 be closed in order to place the system in an enabledcondition.

Finally, when the circuit is enabled, meaning that the relay 30 isenergized and that it has closed its contact 30c in FIG. 3, a circuit iscompleted from the power line P in FIG. 2 through the switch Y and theflasher F, through the contacts Q3 and Q1 and through the jack J6, inFIG. 3, to the then-closed contacts 300, and from there through thecontacts J5 to the ratchet stepping motor M. Also, power is additionallysupplied from the jack J6 through the then-closed contacts 30c and tothe jack J7 which is connected in series with the automanual switch C.As soon as one of the relays 31, 32 or 33 is closed by a subsequent toneoperating one of the relays 41, 42 or 43, one of the normally-closedrelay contacts 31c, 320 or 33c becomes opened and breaks the connectionof power from the auto-manual switch, which would normally actuate theratchet motor M through the jack J5. Thus, it will be seen that thetraflic-light controller K is thereby disconnected both as to manual andautomatic operation, and then is fully controlled by themodulation-sensitive actuator 21.

However, when the modulation-sensitive actuator 21 has taken overcontrol of the traffic controller K, thereby disconnecting the ratchetmotor M from the auto-manual switch C, the current which is supplied tothe ratchet motor is intermittent since it comes through theintermittent flasher K through the contact Q1 before it arrives at thejack J6. Therefore, since the power to the ratchet motor is furnishedintermittently because of the action of the flasher R, the ratchet motoris caused to step rapidly around, performing one step each time theflash contacts F open. In the meantime, current is being suppliedthrough one of the auxiliary switch contacts 45, 46 or 47 to the hashmagnet Q, that is, until this current is broken by opening of that camswitch. For instance, if a 3GO-cycle tone has been received and hasclosed the relay 31, then power will be supplied to the flash magnet Qthrough the contact 31e and through the auxiliary cam 45, and will causeoperation of the flash magnet Q, but only until the cam shaft S hasstepped around sufliciently to open the contacts connected with the cam45. When this occurs, the flash magnet Q is no longer energized, currentis broken through the contacts Q1, Q2 and Q3, and therefore the ratchetmotor ceases to step the shaft 5 around, and whichever ones of thelights 1G, 1A, IR, 26, 2A or 2R are connected to power in thatparticular position of the cam shaft S remain lighted. In thisparticular instance, as illustrated, the tratfic light 1R would be redsince its cam switch is closed and the lights 1G and 1A would remainoff, since their contacts are open. On the other hand, the traflic light26 is energized since its cam switch is closed, and contacts 2A and 2Rremain open. Therefore, the main highway light is red, and thecross-street light is green according to this particular set ofcircumstances.

A similar circuit could be followed through in which the cam switch 46when receiving current through the relay contact 32e, FIG. 3, wouldlight the 1G trafiic light and extinguish the light 1 R, and would lightthe traflic light 2R, but extinguish the light 2G.

The third cam position 47 would be associated with one of the other camsshown at the right end of the cam shaft in dotted lines in order toprovide a left-turn signal or some other more complicated function.

Thus, rec-apitulating, when the relay 30 closes along with one of theother relays, such as the relay 31, the circuit through theautomatic-manual control switch C is opened and therefore thesynchronous timing motor no longer controls the pulsed power to theratchet motor M, which power is instead furnished to the motor M throughthe jack J6 from the contact Q1 of the flash magnet. It the light is redin the preferred direction from which the emergency vehicle is coming,the switch at the auxiliary cam 45 will be closed and the flash magnet Qwill be energized so as to cause the lights in the intersection to allchange from steady state to flashing. They continue flashing while atthe same time the ratchet motor steps the shaft S rapidly around witheach breaking of the flasher contacts F. As soon as the shaft S reachesthe position such that the one light is red, and the other and preferredlight in the intersection is green, the cam 45 opens its associatedswitch and breaks the flow of current to the flash magnet at the rightend thereof. When this happens, the system stops and remains dormantwith the light green in the direction of the street from which theemergency vehicle is coming and with the light red on the other street.The situation remains stable as long as the timer 35 in FIG. 3 has notyet finished its operation. When the timer has run its course, it opensits normallyclosed switch 35a, thereby opening the relay 30 which opensthe then-closed contacts 30a and breaks the flow of power to whicheverone of the relays 31, 32 or 33 has been energized. The whole system is.thereby reset to normal and the automatic-manual switch C is then againconnected through the normally-closed contacts 316, 32c and 33c to theratchet motor so that the actuation of the ratchet motor is controlledby the switches I and R on the synchronous timing motor N. As statedabove, the person driving the emergency vehicle may be in a strangeportion of the city and therefore may not know which of the buttons topress in order to gain the rightof-way for his vehicle at the nextcontrolled intersection. If he presses the wrong one, he defeats hispurpose by making the light turn red against his approaching vehicle.Therefore, the symbols shown at the very top of FIG. 1, and perhapsother or difierent symbols, are provided on the push buttons 2, 3 and 4,and in addition the service poles near the controlled intersection willdisplay discs showing the symbol corresponding with the button whichshould be depressed in order to gain right-of-way through the particularintersection. As related above, if the light is already green in thepreferred direction and the operator depresses the correct button in theemergency vehicle, nothing happens because the cam shaft is already inthe right position and remains so because the opening of one of thecontacts 31c, 32c or 33c disconnects the ratchet motor M from theautomatic-manual switch C. On the other hand, if the light is againstthe approaching emergency vehicle, then the traflic lights in bothdirections are caused to flash for an interval of a few seconds whilethe shaft S steps rapidly around until it reaches the correct positionas determined by one of the auxiliary cams 45, 46 or 47. When thisoccurs, the system stabilizes and remains in this position until thetimer 35 opens all of the relays 30, 31, 32 or 33 and returns control ofthe traffic signal to the synchronous motor M.

I do not limit my invention to the exact 'form shown in the drawings,for obviously changes may be made therein within the scope of theappended claims.

-I claim:

1. A remote-control system for actuating an automatic trafliclightcontroller to present a go light in a favored direct-ion of traveldetermined by an emergency vehicle approaching the controlledintersection, said controller having a switching dial rotated by powerfrom a power source and cyclically actuating a stepping motor forstepping around a shaft having rotary switches each controlling one ofthe traffic lights of said intersection and the controller includingrapid light-flasher means, said remote-control system comprising in thevehicle transmitter means for emitting a carrier signal, pluralmodulation generator means each connected to uniquely modulate thecarrier signal to indicate a favored direction of travel, and selectivemeans for applying at least one of said modulations to the carriersignal; and said remote-control system comprising at said controllerreceiver means for receiving the modulated carrier signal, plural tunedrelay means connected to the receive-r and each responsive to thepresence of one of said unique modulations to operate a plurality ofassociated contacts in each relay means, including first normallyclosedcontacts coupling the switching dial to the stepping motor and openingto break said coupling when a relay means is actuated, secondnormallyopen contacts closing when the relay means is actuated toconnect the stepping motor to the flasher means to step the shaft aroundat the rapid flashing rate, third normallyopen contacts connected withsaid power source and closed when the rleay means is actuated, andseparate auxiliary rotary switches each turned by said shaft andassociated with a different relay means and each connected between oneof said third contact means and the flasher means, each auxiliary switchbeing open when the shaft is positioned to present a go light in theassociate favored direction of travel and closed in other positions,whereby the flasher means is energized only when the shaft is in aposition other than that corresponding with the unique modulationenergizing the associated relay means.

2. In a system as set forth in claim 1, each modulation generatorcomprising an audio frequency generator including a tuning-forkstabilized oscillator.

3. In a system as set forth in claim 1, each of said relay meanscomprising a resonant-frequency sensitive relay tuned to the frequencyof one of said modulation generators.

4. In a system as set forth in claim 1, 'an interval timer at thecontroller and connected to be energized by said relay means;hold-contact means in series with the relay winding of each relay meansto hold the latter closed when energized; and contact means on the timerand connected in series with said hold-contact means for opening therelay means at the end of the timed interval.

5. In a system as set forth in claim 4, each relay means representing aunique traffic direction having sets of normally-closed contactsconnected in series with the windings of the other relays representingother traffic directions whereby when one of these relay means isactuated the other relay means are disabled.

6. In a system 'as set forth in claim 1, said means for selectivelyapplying modulation to the carrier signal in cluding push-lbuttons eachhaving switch means for connecting one of the modulation generators tothe transmitter means when the push-button is pressed and then released;and dash-pot means coupled with each pushbutton and slowing the returnrate thereof when released to provide the transmitted signal withsuflicient duration to operate the receiver means.

7. A remote-control system for actuating an automatic trafiicli-ghtcontroller to present a go light in a favored direction of traveldetermined by an emergency vehicle approaching the controlledintersection, said controller having a switching dial rotated by poweriron].- a power source and cyclically actuating a stepping motor forstepping around a shaft having rotary switches each controlling one ofthe trafi'ic lights of said intersection and the controller includingrapid light-flasher means, said remotecontrol system comprising in thevehicle transmitter means for emitting a carrier signal, pluralmodulation generator means including a coding generator for connectingthe controller for remote control and plural direct-ion identifyinggenerators each connected to uniquely modulate the carrier signal toindicate a favored direction of travel,

and selective means for applying the modulations from said codinggenerator and from one of said identifying generatiors to the carriersignal; and said remote control system comprising at said controllerreceiver means for receiving the modulated carrier signal, plurm tunedrelay means connected to the receiver and each responsive to thepresence of one of said modulations to operate a plurality of associatedcontacts in each relay means, the relay means responsive to the codingmodulation having contacts for enabling energization of the other tunedrelay means and the latter each including first normally-closed contactscoupling the switching dial to the stepping motor 0 and opening to breaksaid coupling when a relay means is actuated, second normally-opencontacts closing when the relay means is actuated to connect thestepping motor to the flasher means to step the shaft around at therapid flashing rate, third normally-open contacts connected with 5 saidpower source and closed when the relay means is actuated, and separateauxiliary rotary switches each turned by said shaft and associated witha different relay means and each connected between one of said thirdcontact means and the flasher means, each auxiliary switch 0 being openwhen the shaft is positioned to present a go light in the associatefavored direction of travel and closed in other positions, whereby theflasher means is energized only when the cam shaft is in a positionother than that correspondmg with the unique modulation energizing theassociated relay means.

8. In a system as set forth in claim 7, each modulation [generatorcomprising an audio frequency generator ineluding a tuning-forkstabilized oscillator.

9. Ina system as set forth in claim 7, each of said relay meanscomprising a resonant-frequency sensitive relay tuned to the frequencyof one of said modulation generators.

10. In a system as set forth in claim 7, an interval timer at thecontroller and connected to be energized by said code-modulationresponsive relay means; hold-contact means in series with the relaywinding of each relay means to hold the latter closed when energized,and contact means on the timer and connected in series with thehold-contact means on the code-modulation responsive relay means foropening the relay means at the end of the timed interval.

11. In a system as set forth in claim 10, each relay means representinga unique tratfic direction having sets of normally-closed contactsconnected in series with the windings of the other relays representingother traflic directions whereby when one of these relay means isactuated the other relay means are disallrled.

12. 'In a system as set forth in claim 7, said means for selectivelyapplying modulation to the carrier signal including push-buttons eachhaving switch means for connecting one of the modulation generators tothe transmit- -ter means when the push-button is pressed and thenreleased; and dash-pot means coupled with each pushbutton and slowingthe return rate thereof when released to provide the transmitted signalwith sufiicient duration to operate the receiver means.

13. In a system as set forth in claim '12, the switching meansassociated with each push-button having two circuits, one circuit ateach switching means energizing the coding generator and the othercircuit energizing a unique direction identifying genera-tor each timethe button is depressed and released.

14. A remote-control system for actuating an automatic traffic-lightcontroller to present a go light in a favored direction of traveldeter-mined from a remote position observing the controlledintersection, said controller having a switching dial rotated by powerfrom a power source and cyclically actuating a stepping motor forstepping around a shafit having rotary switches each controlling one ofthe traflic lights of said intersection, said remotecontrol systemcomprising at the remote position a. transmitter for emitting a carriersignal and including plural modulation means each seleotible to uniquelymodulate the carrier signal to indicate a favored direction of travel;and said control system comprising at said controller pulsating means;receiver means for receiving the moduiated carrier signal, plural tunedmodulation-sensitive means connected to the receiver and each responsiveto the presence of a unique modulation to operate a plurality ofassociated contacts in each tuned means, including first normally-closedcontacts coupling the switching dial to the stepping motor and openingto break said coupling when a tuned means is actuated, secondnormally-open contacts closing when the tuned means is actuated toconncct the stepping motor to the pulsating means to step the shaftaround at a rapid rate, third no-nnrally-open contacts connected withsaid power source and closed when the tuned means is actuated, andseparate auxiliary rotary switches each turned by said shaft andassociated with a different tuned means and each connected between oneof said third contact means and the pulsating means, each auxiliaryswitch being open when the shaft is positioned to present a go light inthe associate favored direction of travel and closed in other positions,whereby the pulsating means is energized only when the shaft is in aposition other than that corresponding with the unique modulationcomprising the associated tuned means.

References Cited in the file of this patent UNITED STATES PATENTS3,020,522 Lcsher Feb. 6, 196 2

14. A REMOTE-CONTROL SYSTEM FOR ACTUATING AN AUTOMATIC TRAFFIC-LIGHTCONTROLLER TO PRESENT A "GO" LIGHT IN A FAVORED DIRECTION OF TRAVELDETERMINED FROM A REMOTE POSITION OBSERVING THE CONTROLLED INTERSECTION,SAID CONTROLLER HAVING A SWITCHING DIAL ROTATED BY POWER FROM A POWERSOURCE AND CYCLICALLY ACTUATING A STEPPING MOTOR FOR STEPPING AROUND ASHAFT HAVING ROTARY SWITCHES EACH CONTROLLING ONE OF THE TRAFFIC LIGHTSOF SAID INTERSECTION, SAID REMOTECONTROL SYSTEM COMPRISING AT THE REMOTEPOSITION A TRANSMITTER FOR EMITTING A CARRIER SIGNAL AND INCLUDINGPLURAL MODULATION MEANS EACH SELECTIBLE TO UNIQUELY MODULATE THE CARRIERSIGNAL TO INDICATE A FAVORED DIRECTION OF TRAVEL; AND SAID CONTROLSYSTEM COMPRISING AT SAID CONTROLLER PULSATING MEANS; RECEIVER MEANS FORRECEIVING THE MODULATED CARRIER SIGNAL, PLURAL TUNEDMODULATION-SENSITIVE MEANS CONNECTED TO THE RECEIVER AND EACH RESPONSIVETO THE PRESENCE OF A UNIQUE MODULATION TO OPERATE A PLURALITY OFASSOCIATED CONTACTS IN EACH TUNED MEANS, INCLUDING FIRST NORMALLY-CLOSEDCONTACTS COUPLING THE SWITCHING DIAL TO THE STEPPING MOTOR AND OPENINGTO BREAK SAID COUPLING WHEN A TUNED MEANS IS ACTUATED, SECONDNORMALLY-OPEN CONTACTS CLOSING WHEN THE TUNED MEANS IS ACTUATED TO CON-